47 research outputs found

    Reproductive potential of the black bean aphid (Aphis fabae Scop.) on a range of faba bean (Vicia faba L.) accessions

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    The black bean aphid is one of the main insect pests of faba bean, leading to yieldlosses in many countries. The aphid inflicts damage to faba bean through directphloem feeding and indirectly by transmission of several viruses. Sources of geneticresistance or tolerance to the aphid have been hard to identify and to use in breedingbecause of the high environmental variability of the attack, the weak and partialnature of the resistance when found, and the low repeatability of experiments. Arange of molecular genotyping tools is now available for identifying the genes under-lying key traits in faba bean. Hence, we screened the responses of eight inbred lines(Columbo, Albus, Closed-flower, Diana, Hedin/2, Icarus, ILB938/2, and Mélodie/2) offaba bean, derived from commercial cultivars and experimental germplasm, to aphidinfestation in controlled (no-choice-test) and field (preference test) conditions. In thecontrolled environment, aphid performance was assessed by measuring fecundityand determining the intrinsic rate of natural increase (rm). In the field experiment,population growth was examined on Columbo, Closed-flower, Hedin/2, andILB938/2 during June and July. Each week, 10 plants in each plot, randomly chosenat the start, were screened for aphid colonization and number of plants attacked. Foreach plant, an index number was given reflecting the severity of aphid presence. Ourresults demonstrate a clear conformity between the results obtained from the indoorpot experiments and the field experiments. In both experiments, ILB938/2 showedpartial resistance with significantly lower fecundity,rm, and field infestation whencompared with the known susceptible line Columbo. The consistently strong perfor-mance of ILB938/2 against the black bean aphid suggests that it carries a factor orfactors rendering it unconducive to aphid landing, feeding, and/or reproduction. Fur-ther investigation into the resistance mechanisms of ILB938/2 is planned

    Use of Fly Screens to Reduce Campylobacter spp. Introduction in Broiler Houses

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    Fly screens that prevented influx of flies in 20 broiler houses during the summer of 2006 in Denmark caused a decrease in Campylobacter spp.–positive flocks from 51.4% in control houses to 15.4% in case houses. A proportional reduction in the incidence of chicken-borne campylobacteriosis can be expected by comprehensive intervention against flies in broiler production houses

    Flies and Campylobacter Infection of Broiler Flocks

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    A total of 8.2% of flies caught outside a broiler house in Denmark had the potential to transmit Campylobacter jejuni to chickens, and hundreds of flies per day passed through the ventilation system into the broiler house. Our study suggests that flies may be an important source of Campylobacter infection of broiler flocks in summer

    Genome-wide fitness analyses of the foodborne pathogen Campylobacter jejuni in in vitro and in vivo models.

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    Campylobacter is the most common cause of foodborne bacterial illness worldwide. Faecal contamination of meat, especially chicken, during processing represents a key route of transmission to humans. There is a lack of insight into the mechanisms driving C. jejuni growth and survival within hosts and the environment. Here, we report a detailed analysis of C. jejuni fitness across models reflecting stages in its life cycle. Transposon (Tn) gene-inactivation libraries were generated in three C. jejuni strains and the impact on fitness during chicken colonisation, survival in houseflies and under nutrient-rich and -poor conditions at 4 °C and infection of human gut epithelial cells was assessed by Tn-insertion site sequencing (Tn-seq). A total of 331 homologous gene clusters were essential for fitness during in vitro growth in three C. jejuni strains, revealing that a large part of its genome is dedicated to growth. We report novel C. jejuni factors essential throughout its life cycle. Importantly, we identified genes that fulfil important roles across multiple conditions. Our comprehensive screens showed which flagella elements are essential for growth and which are vital to the interaction with host organisms. Future efforts should focus on how to exploit this knowledge to effectively control infections caused by C. jejuni.This work was funded by Biotechnology and Biological Sciences Research Council (http://www.bbsrc.ac.uk) grant BB/K004514/1. D.P.W. was funded by a Wellcome Trust (https://wellcome.ac.uk) Infection and Immunity PhD rotation studentship. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
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